Expansion of Treasure Chest subroutine

Update: So, I was able to add rare items and Espers to the list of possible treasures and I played the game a couple of times to make sure there was no bug. So far, so good. However, I'm now looking to modify the Field DTE so that I can add Esper and Rare Item names dynamically in a dialog (therefore, preventing me from having to add every possible "Obtained Esper X" as individual dialogs). I'm trying to use breaks around the creation of a dialog, but I have trouble finding where the special characters ($00 to $1F) are generated specifically. Can anybody help me on that please? Thanks in advance!